Method of flotation ore separation



Patented Sept. 11, 1934 UNITED STATES PATENT OFFICE 1,973,578 METHOD or FLOTATION one SEPARATION No Drawing. Application March 13, 1931,

Serial No. 522,504

11 Claims.

This invention relates to improvements on flotation methods for separating metallic particles from the nonmetallic particles of ores and the different metallic particles from each other.

Ores containing lead, zinc and iron sulphides have long been separated by standard differential flotation methods and it has been found that the same ores from different localities respond differently to the same treatment, although they are l chemically identical.

Investigations have proven that most ores contain some soluble substance or substances that promote flotation of the minerals after the usual steps to inhibit their flotation have been taken with the result that minerals that should normally come off on the second flotation of the differential process come off on the first.

It is well known among those skilled in this art that copper sulphate and other copper compounds are great activators or promoters in the flotation of many of the numerous sulphide materials. Copper sulphate is commonly added to activate or promote the flotation of zinc sulphide and also to activate or promote the flotation of iron sulphides. Copper sulphate also activates and promotes the flotation of many other sulphides.

One of the outstanding properties of copper salts is that of promoting the flotation of the to different sulphide minerals even when only one or two parts per million are present in the pulp treated by flotation.

It is the object of this invention to eliminate the copper salts or compounds and thereby prevent the indiscriminate activation of the sulphide minerals during the period of grinding and mechanical liberation of the sulphides from the gangue and from each other so that these sulphides may be depressed.

to We have discovered that when a complex zinc, iron ore is ground in a solution of zinc sulphate, the zinc sulphide minerals are coated or in some way protected from the activating influence of the copper salts or compounds liberated during the grinding.

When copper salts or compounds are present in the crude ore, we have discovered that the sulphide minerals are activated during the process of grinding and it becomes impossible to separate them by subsequent differential flotation treatment.

We have found that the deleterious effects of the copper salts can be entirely eliminated, or at least greatly reduced if the grinding is carried out in two steps and in a neutral or slightly acid circult. The grinding necessary to completely unlock many of the complex ores must be extremely fine and in this condition the particles expose a very large surface to the solution and if the copper salts were present in their full strength, the deleterious effects would be very great.

In order to reduce the deleterious effects of the copper salts, the ore is filtered after the first grinding whereby about 90% of the deleterious soluble substances are removed, thereby preventing their activating influence from being exerted at the next or final step of unlocking the minerals when their deleterious effect would be enormous due to the large surface exposed.

After the second grinding and liberation of the different sulphides in the ore, the pulp is again filtered and washed to remove the last trace of these deleterious salts.

It is essential that the circuit be maintained neutral or slightly acid during the entire grinding process so as to. prevent the copper salts or compounds from being precipitated as copper hydrate, copper carbonate, basic copper carbonate or other insoluble copper compounds that would be formed if the circuit were basic. If insoluble compounds were permitted to form, these would not go into solution and consequently would not be removed by the filtering and the washing.

The filtering is preferably accompanied by an acid wash and during the second grinding the pulp is preferably conditioned to take all of the salts into solution.

By grinding the ore in a neutral pulp, filtering, repulping, regrinding in a neutral pulp and refiltering as above described, the deleterious copper salts can be quite completely removed, but by grinding in a pulp containing zinc sulphate, the zinc sulphides will be protected from the activating influence of the copper salts and better result obtained.

Both filtering steps may be followed by an acid wash if desired, and the grinding in the presence of zinc sulfate takes place preferably in the second or re-grinding step rather than in the first grinding step when both steps are employed. Also, each grinding step may take place in acid pulp if desired.

Since a neutral or an acid circuit can be used, the term non-basis will be employed to cover both.

In some ores it is necessary to subject the pulp to a short period of contact called conditioning prior to the steps of separating the sulphide minerals by flotation. This conditioning period is intended primarily to give the chemical substances used in depressing or activatingsome of the minerals a longer period of time, whereby more thorough reaction may be obtained and their influence on the pulp in small quantities be greatly increased.

Having described the invention what is claimed as new is:

1. The method of froth-flotation separation of zinc sulfide ores containing copper compounds which comprises grinding the ore in a neutral pulp containing zinc sulphate to protect the zinc sulfides against the copper compounds, separating substantially all the liquid solution from the solid particles, repulping the ore and subjecting the resultant pulp to froth-flotation treatment.

2. The method of froth-flotation separation of zinc sulfide ores containing copper compounds which comprises, grinding the ore, completely separating the liquid solution from the solid particles, washing the solid particles with an acid wash to remove acid soluble constituents, repulping the ore and subjecting the resulting pulp to froth flotation treatment.

3. The method of froth-flotation separation of zinc sulfide ores containing copper compounds which comprises, grinding the ore with zinc sulphate, to protect the zinc sulfides against the copper compounds, separating substantially all the liquid solution from the solid particles, washing the solid particles with an acid wash to remove acid soluble constituents, repulping the ore and subjecting the resulting pulp to froth flotation treatment.

4. The method of froth-flotation separation of zinc sulfide ores containing copper compounds which comprises, grinding the ore in a non-basic pulp containing zinc sulphate to protect the sulfides against the copper compounds, separating substantially all the liquid solution from the solid particles of ore, repulping the ore and subjecting the resulting pulp to froth flotation treatment.

. 5. The method of froth-flotation separation of zinc sulfide ores containing copper compounds which comprises, grinding the ore in a non-basic pulp, completely separating the liquid solution from the solid particles, washing the solid particles with an acid wash to remove acid soluble constituents, repulping the ore and subjecting the resulting pulp to froth flotation treatment.

6. The method of froth-flotation separation of zinc sulfide ores containing copper compounds which comprises grinding the ore in a non-basic pulp containing zinc sulphate, to protect the zinc sulfides against the copper compounds, separating substantially all the liquid solution from the solid particles, washing the solid particles with an acid wash to remove acid soluble constituents, repulping the ore and subjecting the resulting pulp to froth flotation treatment.

'7. In a froth-fiotation-method of separating minerals, the steps of grinding a zinc sulfide ore containing a copper compound in a non-basic solution, filtering, regrinding in a zinc sulfate solution, filtering and subjecting the pulp to differential froth flotation.

8. In a froth-flotation method of separating minerals, the steps of grinding a zinc sulfide ore containing a copper compound in a non-basic solution, filtering, regrinding in a zinc sulphate solution to protect the zinc sulfide against copper compounds, filtering and subjecting the pulp to a conditioning period and treating for a period of time with chemicals that will depress certain mineral particles, subjecting the resulting pulp to froth flotation treatment for the separation of the minerals that have not been depressed, subjecting the tailing from the first treatment to a conditioning period with chemicals that activates one of the minerals that was previously depressed whereby it can be removed and subjecting to the froth flotation method for separating the activated mineral.

9. In a froth-flotation method of separating minerals, the steps of grinding a zinc sulfide ore containing a copper compound in a non-basic solution, filtering with an acid wash, regrinding in a zinc sulfate solution to protect the zinc sulfide against copper compounds, filtering with an acid wash and subjecting the pulp to differential froth flotation.

10. A method for the froth flotation of ore containing zinc sulfides comprising, grinding the ore in a non-basic pulp to prevent soluble copper salts from being'precipitated in insoluble form, completely removing the solution, and eliminating the soluble constituents from the solids while retaining fiocculated bodies as solids, repulping the ore, and subjecting the repulped ore to froth flotation.

11. A method according to claim 10 wherein the grinding step is conducted in the presence of zinc sulfate.

- JOSEPH P. RUTH, JR.

FREDERIC A. BRINKER. 

